Field of the Invention
The present invention relates to a communication apparatus, a communication method, and a computer-readable storage medium.
Description of the Related Art
Along with a recent increase in video quality, there is an increasing demand for a technique of performing radio transmission of a large amount of data at a high transmission rate. As a technique of achieving a high radio transmission rate, there is known a radio communication technique using a 60-GHz band called a millimeter wave. In IEEE802.11ad as a millimeter wave radio communication standard, a maximum transmission rate of about 6.8 Gbps is defined. In millimeter wave radio communication, there is known a technique of enlarging a communication range by concentrating energy in a specific direction using, as a communication antenna, a beam directional antenna capable of beam steering.
Although millimeter wave radio communication can obtain a high radio transmission rate, a communication path may be blocked by an obstacle such as a human body due to the straightness of a millimeter wave, thereby causing a communication error. From this viewpoint, a system arrangement including a spare communication path is useful to prevent a communication path from being blocked by an obstacle. Japanese Patent Laid-Open No. 2013-511931 describes the arrangement of a radio communication system which includes a plurality of communication links between a transmission station and a reception station and simultaneously transmits data using the plurality of communication links.
As described above, by including a plurality of spare communication paths, it is possible to cope with blockage of a communication path. However, if one receiver is included for one transmitter, there is a situation that it becomes impossible to use a plurality of communication links at the same time, for example, when an obstacle exists near the receiver. Thus, the method of simultaneously transmitting data between one transmitter and one receiver using the plurality of communication links, which is described in Japanese Patent Laid-Open No. 2013-511931, cannot be applied to a radio system in which a situation that there is no communication link between one transmitter and one receiver occurs.
In the above-described radio system in which a situation that no communication link can be ensured between radio stations may occur, it is possible to improve the communication robustness by applying an arrangement including a plurality of reception stations for one transmission station. However, for example, if radio communication is executed by assigning, to a plurality of receivers, a time slot in time division multiplexing communication, it is possible to improve the communication robustness but the communication efficiency deteriorates. If an arrangement for performing multicast communication by setting a plurality of receivers as destination stations is applied, the communication efficiency does not deteriorate. However, if, for example, an omni directivity (non-directional) is applied as an antenna directivity which can be covered by a plurality of receivers, a communication distance is limited, as compared with a case in which a beam directivity (directional) is applied. Therefore, switching the directional antenna from the beam directivity to the omni directivity may cause a communication error, and thus it is impossible to improve the communication robustness.
As described above, in the conventional arrangement, a change in radio environment such as blockage of a communication path by an obstacle like a human body or a change in communication environment caused by movement of a radio set degrades at least one of the communication efficiency and the communication robustness.